1. No category

1

Review of basic concepts and principles of biostratigraphy.

Study of the different biostratigraphic models of
invertebrate fossils in Paleozoic, Mesozoic and Cenozoic.
LIFE RECORD
The Earth is 4.6 by old.
Life has existed on Earth for at least 3.5 by.
Life on this planet has not always been as it is now.
Life on Earth has constantly changed, with new species
evolving as older ones becomes extinct.
The modern biosphere evolved from the earliest beginnings.
2
What is a fossil?
Fossil literally means that ”which is dug up”.
Fossils are any remains, trace or imprint of an
organism that has been preserved in the
Earth’s crust since some geologic time.
Fossils are the remains of ancient organisms which
have been exposed due to weathering.
Value of fossils
1.
Fossils are the major bases for recognizing units of time
in the geologic record and for correlation of deposits
containing them. (Age of rocks)
2.
Fossils serve as evidence of changing environments and
geographic patterns during geologic history.
(paleogeography, paleoclimatology, paleoecology)
3.
Fossils show the course of evolutionary modifications of
organisms during geologic time.
4.
Fossils are part of the physical stratigraphic record
because they provide much of the substance which make
up sediment.
3
Value of fossil (cont.)
1. Fossils are the major bases for recognizing
units of time in the geologic record and
for correlation of deposits containing them.
(Age of rocks & Correlation)
Value of fossils (cont.)
Dating rocks by fossil content
LO: last occurrence
Youngest
Units of
geological
time
5
b
4
3
a
2
Oldest
d
c
e
1
FO: first occurrence
These time units may be of any length whole periods
(say Cambrian to Carboniferous) or small divisions of one period
(Webster, 1987).
4
Value of fossils (cont.)
Stratigraphic
range
Time
unit
6
5
4
3
2
1
Change in fossil assemblages through the vertically repeating
succession of lithologies. Even though some forms persist through
more than one lithology.
(Cooper, Miller & Patterson, 1987)
5
A synchronous first appearance
A diachronous first appearance
6
Value of fossils (cont.)
Correlation by fossils
Oxfordshire
North Yorkshire
(Webster, 1987)
Value of fossils
2. Fossils serve as evidence of changing
environments and geographic patterns
during geologic history.
(paleogeography, paleoclimatology, paleoecology)
7
Gondwanaland reassembled and some of the paleontological links that bind it together.
Mesosaurus, a Permian reptile, occurs in S. Brazil and S. Africa; Glossopteris, a Permian plant
occurs across all of the Gondwana components; Lystrosaurus, a Lower Triassic therapsid reptile
occurs in S. Africa, India, SE. Asia and Antartica; Cynognathus, a Lower Triassic reptile, occurs in
S. America and S. Africa.
Paleoclimatology
Correlation of three cores from the south Atlantic as defined
by changes in the direction of coiling of Globorotalia
truncatulinoides.
Warm
Cold
Warm
Cold
Temperature of surface waters
↑
Abundance of Right-coiling forms ↑
The percentage of right-coiling forms increases with
increasing temperature of the surface waters.
8
Value of fossils
3. Fossils show the course of evolutionary
modifications of organisms during
geologic time.
Value of fossils (cont.)
Evolution
Relative
size of
the body
Size
of the skull
Size and
configuration
of the fore and
hind legs
Eocene
Present
Stages in the evolution of the horse from the Eocene to the Present.
(Seyfert & Sirkin, 1979)
9
Value of fossils (cont.)
Evolution
(3+1 toes)
(single toe)
Early Eocene
Present
Reduction in number of toes in horses
The evolution of the genus Orbulina (planktonic foraminifer)
in the Miocene is an example of rapid evolutionary change over
relatively short time span of 0.5 million years,
in which all intermediate forms are known in
an exceptionally complete
stratigraphical sequence.
O. universa
(16 ma)
Ontogeny recapitulates Phylogeny
O. suturalis
P. glomerosa circularis
P. glomerosa glomerosa
P. sicana
Gs. bisphaericus (16.5 ma)
P. glomerosa curva
Photomicrographs taken from A.Hakyemez, 2007
Northern Cyprus
10
3.8 my
Value of fossils (cont.)
Evolution
The five major mass-extinctions of the Phanerozoic.
(Modified from Sepkoski, 1982)
(Doyle, 1997)
11
Value of fossils (cont.)
Mass extinction
Paleogene-forms
Pg
Paleogene
K
Cretaceous
Cretaceous-forms
Survivor - forms
(Doyle, 1997)
Early Paleocene
3.8 my
12
Value of fossils
4. Fossils are part of the physical stratigraphic record
because they provide much of the substance
which make up sediment (Fossiliferous limestone).
(Observable physical feature of the rock stratigraphic unit)
WHAT TINY THINGS CAN TELL US
The science of Micropaleontology is the study of microfossils,
the microscopic remains of animals, plants and protists
belonging mostly to biological groups of simple organisation
(single cell) and less than a millimetre in size.
• The remains of unicellular and multicellular organisms;
• The dissociated and skeletal fragments of macroorganisms.
13
MICROFOSSILS
Some of the more important groups of microfossils include:
 Foraminifera,
 Calcareous nannofossils / Coccolithophores
 Spores and Pollen,
 Dinoflagellates,
 Radiolarians,
 Diatoms,
 Ostracodes and
 Conodonts.
Micropaleontology is perhaps the largest branch of
paleontology, with many specialists world-wide.
Because of their small size and frequently very high
numerical abundance in rocks and sediments,
microfossils are the most commonly used fossils for
applied research.
They are extremely useful in age-dating, correlation and
paleoenvironmental reconstruction, all important in the
oil, mining, engineering, and environmental industries, as
well as in general geology.
14
Microfossils span the marine environment from the abyssal
plains of the deep sea to the salt marshes of the inter-tidal
zone, the freshwater aquatic environments of rivers and
lakes and the terrestrial realm.
These organisms were extraordinarily abundant and
diverse in the past and continue to be so in modern
environments, in many cases forming the primary elements
in organic productivity cycles and food chains.
The production of these organisms is a basic component of
the global biogeochemical system, intimately linked to
present and past environmental change.
PETROLEUM EXPLORATION
One of the most important applications of
micropaleontology today is in oil exploration.
Petroleum is derived from decayed phytoplankton,
microorganisms that live in the sea.
When phytoplankton die, they sink to the sea floor
where they begin to accumulate.
15
Phytoplankton
Phytoplankton are the autotrophic component of plankton. The
name comes from the Greek terms, phyton or "plant" and πλαγκτος
("planktons"), meaning "wanderer" or "drifter".
Most phytoplankton are too small to be individually seen with the
naked eye. However, when present in high numbers, they may
appear as a green discoloration of the water due to the presence of
chlorophyll within their cells (although the actual color may vary with
the species of phytoplankton present due to varying levels of
chlorophyll or the presence of accessory pigments such as
phycobiliproteins).
http://en.wikipedia.org/wiki/Phytoplankton
Dinoflagellate
Ceratium hirundinella
Phytoplanktons
Diatoms
16
The deposited phytoplankton is covered by other
sediments and pushed deeper into the crust of the Earth,
where it is subjected to higher pressures and
temperatures.
Only then will phytoplankton change structure and become
kerogen, heavy oil and finally light oil, which is used for
petroleum.
This complex process means that not all formerly marine
environments will yield petroleum.
The remains of phytoplankton, microfossils, in petroleumbearing rocks undergo changes in colour because of heat.
Micropaleontologists study their alteration in colour to define
possible areas for oil exploration.
When these fossilised microorganisms are pale or orange
the sediment is immature, when they are brown the rocks
are mature, indicating oil, and when the fossils are black,
they indicate gas.
17
FOSSILISATION
The process by which dead organisms (or parts
of organisms) are transformed to fossils is
known as fossilisation.
When animals or plants (organisms) die, their
fleshy parts quickly decompose or sooner or
later the solid parts of their skeletons or shells
likewise vanish without leaving a trace.
The four phases of FOSSILISATION process
The four phases of
the fossilisation
process, from life,
through death and
on to burial.
Death can occur
through a variety of
factors, and
the processes
which act upon an
organism before
and after burial
determine whether
it is to be preserved
as a fossil in the
sedimentary
record.
(Doyle, 1997)
18
FOSSILISATION
Sketch illustrating the fate of shark remains through the death-burial-erosion cycle.
Width of arrows indicates magnitude of loss-gain factors. Note that the main part of
the shark skeleton is not fossilised because it is cartilaginous.
FOSSILISATION

Rapid formation of a layer of sediment over an
organism protects the residue from mechanical
destruction; it also shuts out the air, slows down or
even stops processes of decomposition.

Decomposition may be prevented or retarded by
burial in soft mud / volcanic ash / low temperature
/ dry air / tar, resin.
19
FOSSILISATION
The conditions for fossilisation are determined by series
special favorable circumstances,
• Comprising quick burial of the organism under a layer of
sediment (Rapid sedimentation encourages good
preservation) or tar or resin, etc.
• The physical and chemical properties of the environment
(including sediment; fine-grained sediments are also good
for preserving fossils because of the low O2 content) (Low
temperature)
• The nature of organic residue itself.
• The conditions to which the fossil containing sediments
were secondarily exposed.
Types of preservation

Unaltered Soft Parts: The organism may be entirely
preserved [soft (organic) and skeletal (inorganic) parts]
because of the protection from bacteria.

Unaltered Hard Parts: The soft part is decomposed, but the
hard part is preserved.
•
•
•
•
•

Calcitic shells
Aragonitic shells
Phosphatic shells
Siliceous shells
Resistant Organic Hard parts
Altered Hard Parts: Many fossils show alteration of their
original structure.
20
Type of preservation
Microfossils
How a dead bivalve becomes a fossil.
The sequence of stages between the death of the organism,
and its preservation in various ways.
(Benton & Harper, 1977)
Types of preservation
Unaltered Hard Parts: The soft part is decomposed, but the hard part is
preserved.
1. Calcitic shells: (CaCO3 : Calcite) It is one of the most widely used
skeletal substance by the animals.
2. Aragonitic shells: (CaCO3 : Aragonite) It is unstable mineral and
tends to be removed in solution or recrystallized into calcite.
3. Phosphatic shells: (Ca3PO4 : Tricalcium phosphate) It is
chemically resistant.
4. Siliceous shells: (SiO2.nH2O: Opal) Amorphous hydrous silica. It
is unstable, unaltered forms are largely restricted to rocks of
Cenozoic age.
5. Resistant Organic Hard parts: Certain organic compounds
(molecules of C, H, O and other elements) are resistant to bacterial
action.
21
Types of preservation
Altered Hard Parts: Many fossils show alteration of their
original structure.
• Change in physical structure
• Change in chemical composition
• Rearrangements of molecules
• Removals of molecules
• Additions of molecules
• Substitions of molecules
Type of preservation
Altered Hard Parts
recrystallization
(Benton & Harper, 1977)
22
Type of Preservation
Recrystallization
Arrangement of the original molecules in crystalline
aggregates. In complete recrystallization the original
microstructure is lost and the shell is converted into a
mosaic of interlocking crystals. (structure change)
Calcite → Calcite
Aragonite → Calcite
Type of Preservation
Dehydration and crystallization
Wall material loses its water
Opal (SiO2.nH2O) → Chalcedony or Quartz (SiO2)
23
Type of preservation
Altered Hard Parts
Replacement
(Benton & Harper, 1977)
Type of Preservation
Replacement
 Solution
of the hard structure of shell
 Deposition
of some other mineral substance in the voids
 Substitution

of one chemical ion for another in a mineral.
Pyritization: Chalcedony/Quartz , Calcite/Aragonite → replaced by
pyrite

Calcitization: Chalcedony/Quartz → replaced by calcite/aragonite

Silicification: Calcite/Aragonite → replaced by chalcedony/quartz

Dolomitization: Calcite/Aragonite → replaced by dolomite

Carbonitization: replaced by carbonate minerals; siderite, rhodocrosite
24
Type of Preservation
Traces of animals

Burrows: are the excavations of an animal made into soft
sediment.

Boring: are holes made by an animal into shells, rock,
wood, or hard sediment.

Coprolites: are the fossilized excrement of animals.
CLASSIFICATION

Classification is the arrangement of things in categories.

The formal arrangement of organisms in the groups of a
hierarchy of taxonomic categories.

Taxonomy: The science of the orderly arrangement of
things.

The systematic classification of organisms.
25

Species are groups of individuals that generally look like
each other and can interbreed together to produce offspring
of same kind. They can’t interbreed with other species.
(Blood relationship) (Biological definition)

Species are assemblages of individuals having identity or
near identity of form and anatomical features, except for sex
differences, and measurable distinctness from other
assemblages.

Apart of the minor differences, all members of a species
share a range of features which they are not shared by any
other species. In other words, they consistently resemble
each other more than members of any other groups.
In order to understand the concept of species, it
is very necessary to take account of the fact that


No two indivuduals are absolutely identical.
Individuals belonging to any one species vary
in size, shape, and many details of external
and internal characters.
Species comprises a population.
26
The concept of the species in
Paleontology
In biology, the term species is used to illustrate morphological
(e.g.shape and size), behavioural (e.g.birdsong and hibernation) and
genetic differences between organisms, and as such is genetically
accepted as the natural taxonomic unit.
A modern definition of a biological species would be ‘a group of
inidividuals that look alike and that are able to interbreed to produce
fertile young’.
In paleontology, the interpretation of fossils as biological species is
important to the interpretation of ancient environments.
The concept of the species in Paleontology
However, without the aid of a time machine, it is impossible to
determine whether groups of fossils were able successfully to
interbreed, although individuals sexes have been recognised for some
fossil groups.
The determination of true species is especially difficult in fossils.
Paleontologists have to rely heavily upon the first part of the definition
of species, and recognise groups which look like each other.
Therefore the morphology of a fossil group has the greatest importance
in paleontology, and the accurate recognition of new species is reliant
on stringest methods to identify accurately both differences and
similarities in shape and form.
27
The concept of the species in Paleontology
Three methods can be used to determine species in
paleontology:
 Morphological resemblence
 Biometry
 Shape analysis
All three are effectively different components of the same process:
the analysis of morphology.
CLASSIFICATION
Morphology of the specimen
to be identified
is compared with a population
Angle of apex, shape of fold,
number of ribs, overall size,etc.
Population of collected specimens
Comparison of a single brachiopod specimen with a large population of
individuals judged to represent a single species. If the morphology
of the individual falls within the range of the large population most
paleontologists would consider that the individual belongs to the same species.
(Cooper, Miller & Patterson, 1987)
28
Cartoon demostrating the concept of taxonomic hierarchy
(Doyle, 1997)
Individals
Species-Homo sapiens: wise man
Genus – Homo: man
Family – Hominidae: human, near humans
Order – Primates : monkeys, apes, men
Class – Mammalia: mammals
Phylum – Chordata: animals with backbones
Kingdom – Animalia : animals
The categories of biological classification within each Kingdom
as illustrated by Homo sapiens.
Open University
29
Linné classification
• Indivuduals
• Species (is fundamental unit)
• Genus
• Subfamily
• Family
• Superfamily
• Suborder
• Order
• Class
• Phylum
• Kingdom
Increasing inclusiveness
The scientific classification of the organisms was created
for the first time by the Swedish naturalist, Linné in 1758.
Species nomenclature
Globigerina bulloides / Globigerina bulloides
Such nomenclature is binominal.
The first name is the name of the genus to which the species
belongs and it is written with an initial capital letter.
The second word is the so-called trivial name and it begins with
a small letter.
Combination of the generic names and species names must be
written in italics or underlined.
30
Species nomenclature
Fixation of names:
Type species is an individual belonging to an assemblage
and is chosen to represent the taxonomic unit.
The type of a species is a particular specimen. This single
individual is called holotype.
Kingdoms
31
All organisms are composed of cells.
There is a fundamental difference between organisms based
on the type of cells:
Prokaryotes lack a well defined cell
nucleus and intracellular organelles
Eukaryotes possess cell nucleus
and specialized organelles
(Doyle, 1997)
Prokaryotes

Archaeobacteria are the most primitive life
forms, probably ancestral to all other life forms—
some can tolerate extremely high temperatures
and hostile chemical environments; others can
live in the absence of oxygen

Eubacteria are slightly more advanced—some
are capable of photosynthesis
32
Eubacteria
(Stromatolites built by Eubacteria)
Bacterial filaments
Modern stromatolites
Precambrian stromatolites
Protists
 Single-celled






organisms, including:
Algae
Dinoflagellates
Diatoms
Calcareous nannoplanktons
Radiolarians
Foraminifers
Affinity to Plants
Affinity to Animals
The preserved microfossils of protists are extremely useful for dating.
33
Protists
Dinoflagellate
Diatoms
Calcareous
nannoplanktons
Protists
Dinoflagellate
Ceratium hirundinella
Diatoms
34
Protists
Planktonic foraminifers
Radiolarians
Adaptation to environment
Ecology is the study of the mutual
relationships between organisms and their
environment, including the rock substrate.
35
Some organisms live on the land, and some live
in the water.
• Land-dwellers are called terrestrial organisms
• Water-dwellers are called aquatic organisms
• Marine (inhabit saline sea water) - salinity of sea water is
about 34 - 36 parts per thousand total dissolved solids, or
about 3.5% salt.
• Non-marine (inhabit freshwater) - salinity of freshwater is
about 1 part per thousand total dissolved solids, or about
0.1% salt. Includes rivers, freshwater lakes, springs,
caves, wells, groundwater.


Brackish (inhabit water of intermediate
salinity) - brackish water is a mixture of fresh
water and sea water, and may be found in
bays, deltas, lagoons, estuaries, harbors,
etc.
Hypersaline - water of very high salinity,
such as the Great Salt Lake, Dead Sea, and
some tropical bays and lagoons with high
evaporation rates.
36
Kinds of Marine environments

Subdivision of the sea floor






Subdivision of the depth zones of the water






Intertidal region
Continental shelf
Continental slope
Abyssal plain
Trench
Littoral zone
Sublittoral zone
Bathyal zone
Abyssal zone
Hadal zone
Subdivision of Marine environment


Neritic environment
Oceanic environment
Neritic
Oceanic environment
Intertidal region
(Boggs, 2001)
37
Marine LIFE - lifestyles
Planktonic organisms:
floating
Nektonic organisms:
swimming
Benthonic organisms:
At the bottom
(Benton and Harper, 1997)
Marine organisms
Modes of life

Planktonic organisms: live free in the sea. They do not
have organs to help them move.

Because of their low body density, they are able to float/
drift.

Nektonic organisms: move actively in search of food by
means of swimming organs.

Benthonic organisms: live in a very close relationship to the
bottom.
38
Benthonic organisms
1. Vagile (mobile / vagrant) organisms: The movement of
them is limited by their contact with the substrate.
2. Sessile (seated) organisms: are fixed to / sit on the
substrate or another organism. Since they do not move,
they are completely under the influence of their
environment. Thus they are excellent environmental
indicators.
• infaunal - living beneath the sediment surface
• epifaunal - living on top of the sediment surface
.
Ecology of Foraminifera

Foraminifera are aquatic organisms, found in both
freshwater and marine environments.

Approximately 5000 species are benthic and live on the
bottom of the ocean, on shells, rock and seaweeds
(epifaunal) or in the sand or mud at the bottom
(infaunal).

About 100 species are planktonic and live in the upper
200 meters of the water column.
39

Foraminifera are found in all marine environments,
from the intertidal to the deepest ocean trenches, and
from the tropics to the poles. Species of foraminifera
can be very particular about the environment where
they live.

In other words, some are abundant only in the deep
ocean, others are found only in brackish estuaries or
salt marshes along the shore, and most live at certain
depths and water temperatures in between.

Because different species of foraminifera are found in
different environments, paleontologists can use their
fossils to determine past environments.

Some foraminifera from
families such as
Allogromidae and
Lagynidae inhabit
freshwater.
Freshwater Foraminifera from Lake Geneva
Gromia brunneri (1,2)
Gromia gemma (3)
Gromia squamosa (4)
Gromia saxicola (5,6)
Gromia linearis (7,8)
http://homepage.univie.ac.at/maria.holzmann/papers/Picture_Gallery.pdf
40
What controls Foraminifera distribution?
There are many parameters which influence foraminiferal
distribution in aquatic life.
 Physical variables (Temperature, Water depth,
Hydrostatic pressure, Light intensity, Sediment type,
Current systems).
 Chemical variables (Salinity, Nutrient and Oxygen,
Dissolved calcium carbonate).
 Biological interactions (Predation and Competition).

Temperature: Each species is adapted to a certain range of
temperature conditions. They cannot tolerate the great variation of
temperature. So temperature acts a barrier of the dispersal of marine
animals.
Every species adapt themselves into a certain range of temperature
conditions to have successful reproduction. This range is very narrow
for low-latitude benthic faunas which is in tropical climate. However,
this range is getting wider throughout polar regions. Stratification of
the oceans show that lower layers of water are progressively colder
than the surface layers. For example, average temperature is 28 ºC
in tropical waters but average less than 4 ºC in the abyssal waters.
Planktonic foraminifers distribute bipolar and show the characteristics
of both southern and northern subtropical waters.
41
How benthic and planktonic foraminifer abundance and general composition change with depth and salinity
(from Armstrong and Brasier, 2004).

Salinity: The concentration of dissolved salts in sea water
varies when there is strong evaporation or a dilution from rain
water or runoff from lands. These changes may affect the
adaptation of marine organisms. For example, Planktonic
foraminifera have a very low tolerance to the salinity changes
(Stenohaline)
Highest diversity of foraminifera inhabit environments with
normal marine salinities (~35 ‰). The low salinity (<17 ‰)
environments such as brackish lagoons and marshes show low
diversity of agglutinated foraminifera and some hyaline forms.
The hypersaline (~40 ‰) waters with high carbonate ion
concentrations are favorable to porcelaneous Miliolina.
42

Light: (amount of light): Light intensity is not thought to control the
distribution of Foraminifera directly, though it may show an indirect control
because symbiotic algae living together with foraminifera need light for
photosynthesis. Floating microscopic plants and some single-cell organisms
in the photic zone are the source of food to other organisms. Thus, the zone
of light penetration in the oceans (the photic zone) is attractive to
foraminifera. Photic zone is affected by water clarity and the incient angle of
Sun’s rays.

Nutrient and oxygen: If the food supply is low, as in deep sea,
foraminiferal densities tend to be high but diversity can be low. However if
the food supply is high, foraminiferal diversities tend to be high. Also, high
rate of nutrients lead the anaerobic conditions thus scarce foraminifera.
Oxygen deficiency does not eliminate foraminifera because of their low
oxygen demand.

Depth: Foraminifera are found from sea level to more than
10000 meters. The relative proportion of planktonic to benthic
species varies according to depth with shallow waters having 0
% and in deep waters (>1000 m) having 100 %. Below 3000
meter only agglutinated foraminifera can be found because of
the solubility of calcium carbonate with increasing depth,
calcareous foraminifera are unknown.

Hydrostatic pressure: Pressure influences foraminifera
indirectly through its effect on the rates of reactions in sea water
and on the solubilities of gases, such as CO2 which is necessary
to the formation of calcium carbonate.
43
How benthic and planktonic foraminifera change with depth and latitude in the Pacific Ocean
from Armstrong and Brasier, 2004.
44

Substrate: may affect the distribution of the foraminifera. At
the bottom of the sea one can have hard rock, gravels, sands,
clays, muds, etc. These conditions affect the distribution of
marine benthonic organisms.
Foraminifera from coarser substrates tend to be thick-walled,
heavily ornamented forms of lenticular or globular shape.
Low energy habitat with fine-grained substrates are attractive
to many infaunal species with thin, delicate and elongate shell.

Dissolved calcium carbonate: Solubility of calcium carbonate
increases with increasing depth. Below 500 m water is considered
undersaturated and calcium carbonate tend to dissolve. Most
carbonate goes into complete solution below 4500-5000 meters.
Below the level of complete carbonate dissolution, only some
agglutinated, but no calcareous foraminifera is found.

Current systems: Currents systems affect the distribution of
sediment and the mechanical action of currents affect the postmortem transport of foraminiferal tests. However, foraminifera are
mostly adapted to calm waters.
45

Biological interactions, such as predation and competition, must also
play a role, although this is poorly understood and difficult to quantify.
When the density of foraminifera becomes great, foraminifera have been
observed to migrate away from the crowded areas.
The main relationship among foraminifera is symbiosis, for example,
between foraminifera and many tiny algae is common.
Selected algae, either chlorophyceans, rhodophyceans, dinophyceans
or diatoms, are found in combination with specific hosts. Because of the
different light preferences of their algae, the foraminifers occupy different
depth ranges in the photic zone (<200 m).
Importance of Foraminiferal Ecology

Despite their small size, Foraminifera are useful to geologist,
paleobiologists and paleoceanographers because of their wide
distribution and their ability to preserve a record of past oceanic
conditions in the calcite of their tests.

Understanding the present-day patterns gives an insight into
oceanic and climatic systems throughout Earth’s history.

Because different species of foraminifera are found in different
environments, paleontologists can use their fossils to determine past
environments.
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
Since planktonic foraminifera are surface seawater dwellers, they
reflect changes in surface seawater, while benthic foraminifera
especially from the deeper regions of oceans, are reliable
representatives of changing bottom water conditions.

If a sample of fossil foraminifera contains many living species, the
present-day distribution of those species can be used to infer the
environment there when the fossils were alive. Even when samples
contain all or mostly extinct species data, such as species diversity,
the relative numbers of planktonic and benthic species which is
planktic/benthic ratio are used to infer past environments.

In addition to using species distributions or to study past
environments, the chemistry of the shell can tell us about the
chemistry of the water in which it grew.

Most importantly, the ratio of stable oxygen isotopes depends
on the water temperature, because warmer water tends to
evaporate off more of the lighter isotopes. Studies of stable
oxygen isotopes in planktic and benthic foraminifer shells have
been used to map past water temperatures. These data help us
understand how climate has changed in the past and thus how it
may change in the future.
Research subject:
Effect of seawater carbonate concentration on foraminiferal
carbon and oxygen isotopes ????
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The relationship of density and diversity
In the most hostile environments, communities commonly display a low
diversity, composed of opportunistic species which reproduce rapidly.
Under normal conditions, communities may be more stable and diverse,
composed of equilibrium species with less need to reproduce rapidly and in
great numbers.
(Doyle, 1997)
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FORAMINIFERA
LIFE CYCLE
Microspheric
forms
Form B
 small initial chamber
 large test
 large number of chambers
 less common in nature
 reproduce asexually
Megalospheric
forms
Form A
 large initial chamber
 small test
 few number of chambers
 more common in nature
 reproduce sexually
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